There are some known techniques for measuring dimensions of patterns located on a semiconductor wafer. It may be needed to measure height (or depth) of a pattern, or a particular feature of a pattern, such as an oxide recess or a fin of a device. One of the techniques to measure height is referred to as a “shadow effect.” The technique uses a detector, located at a specific position with respect to the pattern, where the detector does not receive part of the responsive electrons because of occlusion by portions of the pattern, such as a sidewall, thereby creating a shadow.